OK Steve

In AB:

[AMBE_AUDIO]
address = 127.0.0.1                      ; IP address of xx_Bridge.py
TXPort = 31103                          ; Transmit TLV frames to partner on this port
RXPort = 31100                          ; Listen for TLV frames from partner on this port


in  MB DVSwitch:
[DMR]
Address = 127.0.0.1             ; Address to send AMBE TLV frames to (export)
TXPort = 31100                  ; Port to send AMBE TLV frames to (export)
RXPort = 31103                  ; Port to listen on (import)
Slot = 2                        ; Export slot

The script
================================
#!/bin/bash

function tune() {
    echo "Tuning to TG $1"
python - <<END
#!/usr/bin/env python
import sys
import socket
import struct
cmd = "txTg=$1"
_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
cmd = struct.pack("BB", 0x05, len(cmd))[0:2] + cmd
_sock.sendto(cmd, ('127.0.0.1', 31100))
_sock.close()
END
}

tune $1
======================


It is looks I have sent to AB because RXPort is 31100